AUTHOR=Nie Ziyan , Li Wenhua , Deng Lili , Gao Kai , Liu Qinghua , Zhou Zhichun 

TITLE=Comprehensive analysis of LRR-RLKs and key gene identification in Pinus massoniana resistant to pine wood nematode

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.1043261

DOI=10.3389/fpls.2022.1043261

ISSN=1664-462X

ABSTRACT=<p><italic>Pinus massoniana</italic> is a pioneer tree widely planted for afforestation on barren hills in southern China where the total planted area is 8.04 million ha. The invasive pine wood nematode (<italic>Bursaphelenchus xylophilus</italic>) poses a serious threat to the survival of <italic>P. massoniana</italic>. Plant resistance genes encoded by leucine-rich repeat-containing transmembrane-receptor proteins play important roles in plant defense. Leucine-rich repeat receptor-like kinases (LRR-RLKs), the largest subfamily of the RLK protein family, play an important role in sensing stress signals in plants. However, the LRR-RLKs of <italic>P. massoniana</italic> have not been characterized previously, and their role in resistance to <italic>B. xylophilus</italic> is unknown. In this study, 185 members of the LRR-RLK subfamily were identified in <italic>P. massoniana</italic> and were categorized into 14 subgroups. Transcriptomic and quantitative real-time RT-PCR analyses showed that <italic>PmRLKs32</italic> was highly expressed in the stem tissue after inoculation with <italic>B. xylophilus</italic>. The gene exhibited high homology with <italic>AtFLS2</italic> of <italic>Arabidopsis thaliana</italic>. <italic>PmRLKs32</italic> was localized to the plasma membrane and was significantly upregulated in nematode-resistant and nematode-susceptible individuals. The transient expression of <italic>PmRLKs32</italic> resulted in a burst of reactive oxygen species production in <italic>P. massoniana</italic> and <italic>Nicotiana benthamiana</italic> seedlings. These results lay a foundation for further exploration of the regulatory mechanism of LRR-RLKs in response to biotic stress in <italic>P. massoniana</italic>.</p>