Arabidopsis HSP70‐16 is required for flower opening under normal or mild heat stress temperatures

Abstract

Sepals play important roles in protecting inner floral organs from various stresses and in guaranteeing timely flower opening. However, the exact role of sepals in coordinating interior and exterior signals remains elusive. In this study, we functionally characterized a heat shock protein gene, Arabidopsis HSP70‐16, in flower opening and mild heat stress response, using combined genetics with anatomic, physiological, chemical, and molecular analyses. We showed that HSP70‐16 is required for flower opening and mild heat response. Mutation of HSP70‐16 led to a significant reduction in seed setting rate under 22°C, which was more severe at 27°C. Mutation of HSP70‐16 also caused postgenital fusion at overlapping tips of two lateral sepals, leading to failed flower opening, abnormal floral organ formation, and impaired fertilization and seed setting. Chemical and anatomic analyses confirmed specific chemical and morphological changes of cuticle property in mutant lateral sepals, and qRT‐PCR data indicated that expression levels of different sets of cuticle regulatory and biosynthetic genes were altered in mutants grown at both 22°C and 27°C temperatures. This study provides a link between thermal and developmental perception signals and expands the understanding of the roles of sepal in plant development and heat response.

HSP70‐16 and VDAC3 jointly inhibit seed germination under cold stress in Arabidopsis

“…To further explore the function of HSP70‐16 in addition to its function in sepal fusion (Chen et al ., 2019) we screened a sepal cDNA library for its interacting partners, using the full cDNA sequence of HSP70‐16 as a bait. Two potential interacting partners were isolated, including VDAC3 encoded by At5G15090 and CaN2 encoded by At2G40410 .…”

“…All seeds used in this research were from Arabidopsis thaliana ecotype Columbia. Seeds of all TDNA‐insertion mutants were obtained from the Salk institute while those of hsp70‐16 complementation line were generated ourselves (Chen et al ., 2019). Seeds were sterilized, plated on ½ MS plates, and incubated at 4°C for 3 days in the dark.…”

“…In mammals, HSP70s have been reported to act as chaperones, playing crucial roles in stress responses (Hageman et al ., 2011), gene transcriptional regulation (Gao et al ., 2015), intracellular trafficking (Prulière‐Escabasse et al ., 2007) and Ca 2+ signal transduction (Krieger et al ., 2006). In Arabidopsis , HSP70s are known to participate in diverse physiological processes, such as seed germination under both normal (Gallardo et al ., 2001) and heat stress (Su and Li, 2008; Chen et al ., 2019) conditions, yet their involvement in seed germination at low temperature remains elusive (Ray et al ., 2016). In addition, while HSP70s are known to be involved in diverse signaling pathways including those dependent on ABA (Ray et al ., 2016), little is known concerning the association of HSP70s and VDACs with ABA signaling in plants.…”

Heat Shock Responsive Gene Expression Modulated by mRNA Poly(A) Tail Length

“…For example, the gene family of HSP70 and HSP17.6C, which are of special interest, is essential to plant growth and environmental responses. Arabidopsis mutation of HSP70-16 led to a significant reduction in seed setting rate, caused by failed flower opening, abnormal floral organ formation, and impaired fertilization (Chen et al, 2019). Plants with HSP17.6A overexpression could survive longer than the wild-type upon salt stress, where the transgenic plants had high At-HSP17.6A transcript and protein levels (Sun et al, 2001).…”

Efectos genéticos y medio ambientales en la estructura fenotípica de Antirrhinum

“…Por ejemplo, la capacidad de tolerar temperaturas extremadamente altas está relacionada con la expresión de la proteína de choque térmico 101 (Hsp101) y los mutantes se caracterizan por un hipocotilo alargado y una termotolerancia reducida (Hong y Vierling, 2000). Se requiere la expresión de otra proteína de choque térmico de Arabidopsis, HSP19-16, para que bajo estrés por calor leve, los sépalos se separen y las flores se abran por completo, así como para garantizar la formación normal de órganos florales, la fertilización y el establecimiento de semillas (Chen et al, 2019b). La expresión de HSP está mediada por factores de estrés por calor (Hsfs) como transductores de señal a través de la unión de Hsf al elemento promotor del gen de choque térmico (HSE).…”