Plant Biotechnology Journal

Luo, Ming; Wang, Aihua; Chakraborty, Soma; Low, Shyh Yin; Babaei, Saeid; Chen, Jian; Zhang, Jianping; Bhatt, Dhara; Brooks, Brenton; Matny, Oadi; Upadhyaya, Narayana; Mago, Rohit; Figueroa, Melania; Lagudah, Evans; Dodds, Peter; Steffenson, Brian; Ayliffe, Michael

doi: 10.1111/pbi.70692pmid: 42220021

Genetic resistance is the most economical and sustainable approach for crop protection, however, it is regularly overcome by pathogen virulence evolution. Polygenic resistance has greater durability, but unlinked genes are laborious to maintain in breeding programs. Introducing cloned resistance genes into the genome as gene stacks enables polygenic resistance with single locus inheritance. Fielder and Robin wheat plants were generated carrying two loci that each encode five wheat stem rust resistance transgenes, that is, Sr13c/Sr21/Sr22/Sr26/Sr33 and Sr22/Sr35/Sr45/Sr50/Sr55. Multiple transgenic events were combined and tested in the field. These lines, with unprecedented levels of transgenic resistance (i.e., 10 transgenes encoded on 90 kb of sequence), showed stable gene stack inheritance and transgene expression after eight generations and were highly resistant in the field. Importantly, in the absence of disease pressure no reproducible differences in the agronomic performance of transgenic lines that contained either one or both gene stacks was seen compared with control lines over two field trial seasons. These data confirm resistance gene stack efficacy and viability as a novel durable resistance strategy in agricultural crop production. Furthermore, this isogenic material that differs only by polygenic resistance provides significant insight into the broader question of the cost of disease resistance in host plants.

Luo, Yuechuan; Duan, Zongbiao; Li, Juxu; Zhu, Zhou; Wu, Tong; Li, Dan; Liu, Yangping; Xu, Liangwei; Wen, Hao; Shen, Yanting; Liu, Shulin; Li, Qingtian; Tian, Zhixi

doi: 10.1111/pbi.70701pmid: 42310878

Seed size plays an important role in determining crop yield, yet the genetic mechanisms underlying the regulation of this agronomic trait remain incompletely understood in soybean. Here, we perform a genome‐wide association study mapping with seed length variations and identify a major quantitative trait locus (QTL) on chromosome 20, named SL20 (Seed Length 20). GmSL20 encodes a TGA‐type bZIP transcription factor that controls soybean seed size and weight in natural populations. Knockout of GmSL20 suppresses seed enlargement and lipid biosynthesis in soybean, whereas increased expression of GmSL20 improves seed size and oil content. Further functional investigations reveal that GmSL20 directly activates GmST05 and GmZF351, thus promoting carbon partitioning to seeds. A super allele that arose from domestication confers elevated capacity for DNA binding and transcriptional activation to GmSL20. It correlates with larger seed size in haplotype analysis and enhances seed size and weight in elite soybean variety; however, it has not been widely fixed and spread through modern breeding. The role of GmSL20 to promote yield and quality underscores its potential as a valuable resource for soybean breeding programs seeking to improve both traits simultaneously.

Xu, Yunfeng; Sun, Haoran; Liu, Lijun; Liang, Qiyu; Shen, Ling; Han, Ailing; Fu, Liangbo; Wang, Fengyue; Xie, Shanggeng; Xiong, Jiangyan; Tu, Yishan; Xu, Zhengyuan; Cai, Kangfeng; Ye, Lingzhen; Cai, Shengguan; Chen, Zhong‐Hua; Wu, Dezhi; Zhang, Guoping; Shen, Qiufang

doi: 10.1111/pbi.70693pmid: 42281511

Soil salinity is a major abiotic stress that threatens global crop productivity. Calcium (Ca2+) is a pivotal second messenger in plant stress signalling, but how Ca2+ sensors such as calmodulin (CaM) transcriptionally control ion homeostasis and salt tolerance remains largely understood in crops. Here, we identified a novel calmodulin‐binding protein HvCBP60b, which is a negative regulator of salt resilience in salt‐tolerant barley. We showed that HvCBP60b interacts with Ca2+ sensor HvCaM1 via its C‐terminal domain in a Ca2+‐dependent manner. Loss of either HvCBP60b or HvCaM1 promoted the uptake of K+, increased the K+/Na+ ratio, and markedly enhanced both growth performance and grain yield under salinity stress. Furthermore, HvCBP60b binds to the promoter of R2R3‐type MYB transcription factor HvMYB77 through its N‐terminal domain. HvMYB77 then transcriptionally reduces the expression of HvHAK5, a high‐affinity K+ transporter essential for maintaining K+ homeostasis under salinity. Mutations in HvMYB77 or HvHAK5 compromise salt tolerance, whereas the salt‐sensitive phenotype of hvhak5 is rescued in hvcbp60b‐hvhak5 double mutants. Therefore, we uncover a novel Ca2+‐responsive regulatory module CaM1‐CBP60b‐MYB77‐HAK5 essential for K+ homeostasis and salt tolerance in barley, highlighting new targets of Ca2+ signalling for improving salt resilience in cereal crops.

Li, Shubin; Sun, Tao; Liu, Dailin; Zhang, Tong; Chen, Lei; Zhang, Weiwen

doi: 10.1111/pbi.70702pmid: 42298770

The single crossover occurring via homologous recombination is a common phenomenon existing among microbes like Escherichia coli, Bacillus subtilis, Vibrio natriegens, Gluconobacter oxydans and most cyanobacteria species, threatening the stability of engineered strains and challenging iterative genetic engineering. Among them, we take the fast‐growing cyanobacterium Synechococcus elongatus UTEX 2973 (Syn2973) as a representative study due to its promising roles for CO2 fixation and bioconversion. We established three marker‐free platforms to achieve stable genome recombination: (i) T4CROSS, which employs two plasmids and four rounds of single crossover; (ii) TRIPLEARM, which uses a single plasmid containing three homologous arms for three rounds of single crossover; and (iii) CRISPRARM, which integrates CRISPR/Cpf1‐mediated genome editing with homologous recombination. As proof of concept, we employed the CRISPRARM platform for a three‐step sequential engineering of the sucrose biosynthetic pathway. The final engineered strain produced 7.12 g L−1 of sucrose within 4 days.

Kim, Byeong‐Hoon; Lee, Yeo Jin; Choi, Yong Jin; Lim, Sooyeon; Park, Young Jin; Kim, Jae Kwang; Ha, Sun‐Hwa

doi: 10.1111/pbi.70697pmid: 42261908

Zhao, Luyan; Song, Na; Wang, Lei; Wu, Jinsong

doi: 10.1111/pbi.70703pmid: 42287000

Jasmonate (JA) regulates defence responses in plants. However, JA‐induced defence often results in growth inhibition. This process is largely mediated by MYC2, the master regulator of JA signalling. Nevertheless, the underlying molecular mechanisms have not yet been fully uncovered. Here, we discovered that the ERF transcription factor NaERFIDOG plays a key role in the JA‐induced defence over growth in Nicotiana attenuata upon infection by the notorious fungal pathogen Alternaria alternata. NaERFIDOG expression was directly controlled by JA through NaMYC2a/b. Plants silenced or knocked out for either NaERFIDOG or both NaMYC2a and NaMYC2b exhibited similar phenotypes: they were both more vulnerable to A. alternata but grew larger. However, stable overexpression of NaERFIDOG increased resistance to the fungus and reduced growth in both wild‐type (WT) plants and those co‐silenced with NaMYC2a/b to a similar extent. Further analysis indicated that NaERFIDOG binds directly to the promoters of the biosynthetic genes for scopoletin, JA and GA, including NaF6'H1, NaAOS and NaKAO1‐like, thereby activating scopoletin and JA biosynthesis while suppressing GA biosynthesis. Finally, our results revealed that both increasing scopoletin levels and reducing GA biosynthesis were involved in JA‐induced disease resistance and growth inhibition. Thus, our study revealed how JA prioritizes defence against A. alternata over growth by a novel regulatory network, JA‐MYC2‐ERFIDOG‐Scopoletin/JA/GA. These findings provide new insights into the molecular mechanisms underlying the trade‐off between defence and growth in plants and highlight the key role of NaERFIDOG in the biosynthesis of scopoletin, JA and GA.

Wen, Fu‐An; Mai, Fu‐Dong; Xiao, Ji‐Bin; Zhang, Hong; Zhou, Xuan; Yang, Xin‐Yu; Sterlin, Yelena; Karpovsky, David; Li, Ke‐Ting; Wang, Juan; Liu, Jia; Su, Shi‐Hao; Mosquna, Assaf; Sun, Yu‐Fei

doi: 10.1111/pbi.70700pmid: 42220070

Abscisic acid (ABA) is a central hormonal regulator of plant adaptation to stress and developmental progression. However, its contribution to agronomic traits such as yield remains unclear due to the pleiotropic nature of ABA signalling. To disentangle distinct physiological functions of ABA, we employed a receptor‐specific gain‐of‐function strategy in tomato, activating downstream signalling independently of endogenous hormone levels in an ABA‐deficient background. This approach revealed two separable ABA‐responsive modules that contribute to yield formation: one enhancing drought resilience through improved stomatal regulation, and another restoring reproductive success by promoting pollen viability and anther development. These physiological responses, governed by spatially distinct sites of ABA action, partially mitigated the yield penalties associated with ABA deficiency, although neither alone was sufficient to fully restore productivity. Our findings establish a dual functional framework by which ABA signalling coordinates water conservation with reproductive fitness, providing mechanistic insight into how hormone signalling integrates stress adaptation with crop yield. This modular understanding lays the foundation for targeted manipulation of ABA pathways to improve agricultural resilience under climate stress.