Divya Dhanasekar, Madhavi Kanaparthi Ratna, Dass Muralidharan Ayyappa, Maku Roshan Venkata, Mallikarjuna Garladinne, Sundaram Raman Meenakshi, Laha Gouri Sankar, Padmakumari Ayyagari Phani, Patel Hitendra Kumar, Prasad Madamsetty Srinivas, Sonti Ramesh Venkata, Bentur Jagadish Sanmallappa
Agri Biotech Foundation, Rajendranagar, Hyderabad, 500030, India.
ICAR-Indian Institute of Rice Research, Rajendranagar, Hyderabad, 500030, India.
Rice (N Y). 2018 Jul 13;11(1):40. doi: 10.1186/s12284-018-0231-4.
Rice, a major food crop of the world, endures many major biotic stresses like bacterial blight (BB), fungal blast (BL) and the insect Asian rice gall midge (GM) that cause significant yield losses. Progress in tagging, mapping and cloning of several resistance (R) genes against aforesaid stresses has led to marker assisted multigene introgression into elite cultivars for multiple and durable resistance. However, no detailed study has been made on possible interactions among these genes when expressed simultaneously under combined stresses.
Our studies monitored expression profiles of 14 defense related genes in 11 rice breeding lines derived from an elite cultivar with different combination of R genes against BB, BL and GM under single and multiple challenge. Four of the genes found implicated earlier under combined GM and BB stress were confirmed to be induced (≥ 2 fold) in stem tissue following GM infestation; while one of these, cytochrome P450 family protein, was also induced in leaf in plants challenged by either BB or BL but not together. Three of the genes highlighted earlier in plants challenged by both BB and BL were also found induced in stem under GM challenge. Pi54 the target R gene against BL was also found induced when challenged by GM. Though expression of some genes was noted to be inhibited under combined pest challenge, such effects did not result in compromise in resistance against any of the target pests.
While R genes generally tended to respond to specific pest challenge, several of the downstream defense genes responded to multiple pest challenge either single, sequential or simultaneous, without any distinct antagonism in expression of resistance to the target pests in two of the pyramided lines RPNF05 and RPNF08.
水稻是世界主要粮食作物，面临许多主要生物胁迫，如白叶枯病（BB）、稻瘟病（BL）和害虫亚洲稻瘿蚊（GM），这些胁迫会导致显著的产量损失。针对上述胁迫的几个抗性（R）基因的标记、定位和克隆研究取得进展，已通过标记辅助将多基因导入优良品种，以实现多重和持久抗性。然而，尚未对这些基因在复合胁迫下同时表达时可能的相互作用进行详细研究。
我们的研究监测了11个源自优良品种的水稻育种系中14个防御相关基因的表达谱，这些育种系具有针对BB、BL和GM的不同R基因组合，处于单一和多重挑战下。先前发现在GM和BB复合胁迫下有牵连的四个基因，在GM侵染后的茎组织中被证实被诱导（≥2倍）；其中一个基因，细胞色素P450家族蛋白，在受到BB或BL单独侵染而非同时侵染的植物叶片中也被诱导。先前在受到BB和BL共同侵染的植物中突出显示的三个基因，在GM挑战下的茎中也被发现被诱导。针对BL的目标R基因Pi54在受到GM挑战时也被发现被诱导。虽然在复合害虫挑战下一些基因的表达被抑制，但这种影响并未导致对任何目标害虫的抗性受损。
虽然R基因通常倾向于对特定害虫挑战做出反应，但几个下游防御基因对单一、相继或同时的多重害虫挑战做出反应，在两个聚合系RPNF05和RPNF08中，对目标害虫的抗性表达没有明显的拮抗作用。
