Functional characterization of PETIOLULE-LIKE PULVINUS (PLP) gene in abscission zone development in Medicago truncatula and its application to genetic improvement of alfalfa

Authors

Juan Du, Noble Research Institute, Ardmore, OK
Shaoyun Lu, South China Agricultural University, Guangzhou
Maofeng Chai, Noble Research Institute, Ardmore, OK
Chuanen Zhou, Shandong University, Qingdao
Liang Sun, Noble Research Institute, Ardmore, OK
Yuhong Tang, Noble Research Institute, Ardmore, OK
Jin Nakashima, Noble Research Institute, Ardmore, OK
Jaydeep Kolape, University of Nebraska - LincolnFollow
Zhaozhu Wen, Noble Research Institute, Ardmore, OK
Marjan Behzadirad, Oklahoma State University
Tianxiu Zhong, South China Agricultural University
Juan Sun, Qingdao Agricultural University
Yunwei Zhang, China Agricultural University, BeijingFollow
Zeng-Yu Wang, Noble Research Institute, Ardmore, OKFollow

ORCID IDs

Jaydeep Kolape https://orcid.org/0000-0002-1787-3313

Zeng-Yu Wang https://orcid.org/0000-0002-6835-7917

Document Type

Article

Date of this Version

2020

Citation

Plant Biotechnology Journal (2020), pp. 1–14

doi: 10.1111/pbi.13469

Comments

(c) 2020 The Authors

This is an open access article under the terms of the Creative Commons Attribution License,

Abstract

Alfalfa (Medicago sativa L.) is one of the most important forage crops throughout the world. Maximizing leaf retention during the haymaking process is critical for achieving superior hay quality and maintaining biomass yield. Leaf abscission process affects leaf retention. Previous studies have largely focused on the molecular mechanisms of floral organ, pedicel and seed abscission but scarcely touched on leaf and petiole abscission. This study focuses on leaf and petiole abscission in the model legume Medicago truncatula and its closely related commercial species alfalfa. By analysing the petiolule-like pulvinus (plp) mutant in M. truncatula at phenotypic level (breakstrength and shaking assays), microscopic level (scanning electron microscopy and cross-sectional analyses) and molecular level (expression level and expression pattern analyses), we discovered that the loss of function of PLP leads to an absence of abscission zone (AZ) formation and PLP plays an important role in leaflet and petiole AZ differentiation. Microarray analysis indicated that PLP affects abscission process through modulating genes involved in hormonal homeostasis, cell wall remodelling and degradation. Detailed analyses led us to propose a functional model of PLP in regulating leaflet and petiole abscission. Furthermore, we cloned the PLP gene (MsPLP) from alfalfa and produced RNAi transgenic alfalfa plants to down-regulate the endogenous MsPLP. Down-regulation of MsPLP results in altered pulvinus structure with increased leaflet breakstrength, thus offering a new approach to decrease leaf loss during alfalfa haymaking process.