Overexpression of FERONIA receptor-like kinase MdMRLK2 enhances apple
cold tolerance by modulating cell wall components, osmotic adjustment
substances and anthocyanin biosynthesis
Abstract
Cold stress is the main abiotic stress in temperate fruit crops,
affecting the yield and fruit quality of apple in China and European
countries. The plant receptor-like kinase FERONIA is involved in abiotic
stresses. However, little is known about its function in apple cold
resistance. In this study, the apple FERONIA receptor-like kinase
encoding gene MdMRLK2 was rapidly induced by cold treatment.
MdMRLK2 overexpression apple plants showed enhanced cold
resistance relative to wild-type. Further analyses indicated that, under
cold condition, MdMRLK2 overexpression apple plants had i)
reduced activities of polygalacturonase, pectinate lyase, pectinesterase
and cellulase; ii) higher contents of water insoluble pectin, lignin,
cellulose and hemicellulose; iii) more soluble sugars and free amino
acids accumulation; iv) reduced photosystem damage. Intriguingly,
MdMRLK2 interacted with MdMYBPA1 and promoted its binding to
MdANS and MdUFGT promoters, leading to increased
anthocyanin biosynthesis. Collectively, these findings unveiled a novel
function of apple FERONIA MdMRLK2 in regulating cold resistance.