title: A Critical Role of Lyst-Interacting Protein5, a Positive Regulator of Multivesicular Body Biogenesis, in Plant Responses to Heat and Salt Stresses.
abstract: Multivesicular bodies (MVBs) are unique endosomes containing vesicles in the lumen and play critical roles in many cellular processes. We have recently shown that Arabidopsis (Arabidopsis thaliana) Lyst-Interacting Protein5 (LIP5), a positive regulator of the Suppressor of K(+) Transport Growth Defect1 (SKD1) AAA ATPase in MVB biogenesis, is a critical target of the mitogen-activated protein kinases MPK3 and MPK6 and plays an important role in the plant immune system. In this study, we report that the LIP5-regulated MVB pathway also plays a critical role in plant responses to abiotic stresses. Disruption of LIP5 causes compromised tolerance to both heat and salt stresses. The critical role of LIP5 in plant tolerance to abiotic stresses is dependent on its ability to interact with Suppressor of K(+) Transport Growth Defect1. When compared with wild-type plants, lip5 mutants accumulate increased levels of ubiquitinated protein aggregates and NaCl under heat and salt stresses, respectively. Further analysis using fluorescent dye and MVB markers reveals that abiotic stress increases the formation of endocytic vesicles and MVBs in a largely LIP5-dependent manner. LIP5 is also required for the salt-induced increase of intracellular reactive oxygen species, which have been implicated in signaling of salt stress responses. Basal levels of LIP5 phosphorylation by MPKs and the stability of LIP5 are elevated by salt stress, and mutation of MPK phosphorylation sites in LIP5 reduces the stability and compromises the ability to complement the lip5 salt-sensitive mutant phenotype. These results collectively indicate that the MVB pathway is positively regulated by pathogen/stress-responsive MPK3/6 through LIP5 phosphorylation and plays a critical role in broad plant responses to biotic and abiotic stresses.
authors.affiliation: Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907-2054 (F.W., Z.W., J.Z., B.F., Z.C.); andDepartment of Horticulture, Zijingang Campus, Zhejiang University, Hangzhou 310058, China (Y.Y., J.Z., Z.C.).
authors.forename: Fei
authors.initials: F
authors.lastname: Wang
authors.affiliation: Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907-2054 (F.W., Z.W., J.Z., B.F., Z.C.); andDepartment of Horticulture, Zijingang Campus, Zhejiang University, Hangzhou 310058, China (Y.Y., J.Z., Z.C.).
authors.forename: Yan
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907-2054 (F.W., Z.W., J.Z., B.F., Z.C.); andDepartment of Horticulture, Zijingang Campus, Zhejiang University, Hangzhou 310058, China (Y.Y., J.Z., Z.C.).
authors.forename: Zhe
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907-2054 (F.W., Z.W., J.Z., B.F., Z.C.); andDepartment of Horticulture, Zijingang Campus, Zhejiang University, Hangzhou 310058, China (Y.Y., J.Z., Z.C.).
authors.forename: Jie
authors.initials: J
authors.lastname: Zhou
authors.affiliation: Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907-2054 (F.W., Z.W., J.Z., B.F., Z.C.); andDepartment of Horticulture, Zijingang Campus, Zhejiang University, Hangzhou 310058, China (Y.Y., J.Z., Z.C.).
authors.forename: Baofang
authors.initials: B
authors.lastname: Fan
authors.affiliation: Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907-2054 (F.W., Z.W., J.Z., B.F., Z.C.); andDepartment of Horticulture, Zijingang Campus, Zhejiang University, Hangzhou 310058, China (Y.Y., J.Z., Z.C.) zhixiang@purdue.edu.
authors.forename: Zhixiang
authors.identifier: http://orcid.org/0000-0002-5472-4560
authors.initials: Z
authors.lastname: Chen
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000378:metabolism*; D004705:Endocytosis / Q000187:drug effects; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006358:Hot Temperature; D007477:Ions; D057146:Multivesicular Bodies / Q000187:drug effects / Q000378:metabolism*; D009154:Mutation / Q000235:genetics*; D001678:Organelle Biogenesis; D010641:Phenotype; D010766:Phosphorylation / Q000187:drug effects; D018517:Plant Roots / Q000187:drug effects / Q000502:physiology; D011485:Protein Binding / Q000187:drug effects; D055550:Protein Stability / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism; D055049:Salt Tolerance / Q000187:drug effects; D012964:Sodium / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology*; D013312:Stress, Physiological / Q000187:drug effects*; D013347:Subcellular Fractions / Q000378:metabolism; D057149:Ubiquitinated Proteins / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D007477:Ions; D017382:Reactive Oxygen Species; D057149:Ubiquitinated Proteins; D049452:Green Fluorescent Proteins; D012965:Sodium Chloride; D012964:Sodium; D000251:Adenosine Triphosphatases; C560560:SKD1 protein, Arabidopsis