Plant Cell|自噬相關14及其相關的磷脂醯肌醇3-激酶複合物促進擬南芥自噬

磷脂醯肌醇3-磷酸(PI3P)是自噬和內體分選的重要膜標誌，在植物中由Ⅲ類磷脂醯肌醇3-激酶(PI3K)複合物合成，PI3K由Vps34激酶、ATG6、VPS15和VPS38或ATG14作為第四亞單位組成。雖然缺少這三個核心亞單位的擬南芥植株是不育的，但vps38突變體是可行的，但具有異常的葉片、根和種子發育、蔗糖感知和內體運輸，這表明VPS38和ATG14是非冗餘的。

在這裡，我們通過一組CRISPR/Cas9和T-DNA插入突變體擾亂兩個擬南芥近緣基因來評估ATG14的作用。Atg14a atg14b雙突變體是相對正常的表型，但在營養脅迫期間表現出自噬缺陷，包括自噬小體積累減少和貨物運輸減少。

出人意料的是，純合atg14a atg14b vps38三重突變體是可行的，但表現出嚴重的玫瑰花結發育，並降低了繁殖力、花粉萌發和自噬，這與ATG14和VPS38都需要完全激活PI3P生物學是一致的。然而，三個突變體仍然積累了PI3P，但對PI3K抑制劑wortmannin敏感，表明ATG14/VPS38組分對PI3P的合成不是必需的。

總而言之，ATG14/VPS38突變體為研究在PI3P生物學植物特定功能提供可能。

Phosphatidylinositol 3-phosphate (PI3P) is an essential membrane signature for both autophagy and endosomal sorting that is synthesized in plants by the class-III phosphatidylinositol 3-kinase (PI3K) complex, consisting of the VPS34 kinase, together with ATG6, VPS15, and either VPS38 or ATG14 as the fourth subunit. While Arabidopsis plants missing the three core subunits are infertile, vps38 mutants are viable but have aberrant leaf, root and seed development, sucrose sensing, and endosomal trafficking, suggesting that VPS38 and ATG14 are non-redundant. Here, we evaluated the role of ATG14 through a collection of CRISPR/Cas9 and T-DNA insertion mutants disrupting the two Arabidopsis paralogs. atg14a atg14b double mutants were relatively normal phenotypically but displayed autophagy defects, including reduced accumulation of autophagic bodies and cargo delivery during nutrient stress. Unexpectedly, homozygous atg14a atg14b vps38 triple mutants were viable but showed severely compromised rosette development and reduced fecundity, pollen germination and autophagy, consistent with a need for both ATG14 and VPS38 to fully actuate PI3P biology. However, the triple mutants still accumulated PI3P, but were hypersensitive to the PI3K inhibitor wortmannin, indicating that the ATG14/VPS38 component is not essential for PI3P synthesis. Collectively, the ATG14/VPS38 mutant collection now permits the study of plants altered in specific aspects of PI3P biology

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