## 3 Lactic Acid Bacteria (LAB): An Emerging Group of PGPR
### Bioprotection Effects of LAB  
LAB have also received considerable attention for their capability to synthesize antifungal metabolites (e.g., diketopierazines, hydroxy derivatives of unsaturated fatty acids, and 3-phenyllactic acid), antibacterial (e.g., bacteriocins and bacteriocin-like substances), and general antimicrobial metabolites (e.g., hydrogen peroxide, organic acids, pyrrolidone-5-carboxylic acid, diacetyl, and reuterin) [133; 134; 135]. In addition to direct antagonism against pathogens, LAB can affect the plant response to pathogens by causing systemic acquired resistance (SAR) and enhancing plant innate immunity [97]. [PERSON] et al. [136] observed that the antibacterial activity of _Lacti plantarum_ DY-6 was dependent on the production of acetic acid, lactic acid, caprylic acid, propionic acid, and decyl acid. On the other hand, [PERSON] et al. [137] observed that the ability to synthesize lactic acid in the bacterial strains without antimicrobial activity was in the same range or even higher than those possessing antimicrobial activity, while the amount of acetic acid corresponded to that normally detected in the culture medium used for assessment tests. Therefore, they concluded that the antimicrobial activity of _Lacti_. _plantarum_, _Latilactobacillus sakei_, _Loigolactobacillus coryniformis_, and _Pediococcus_. _pentosaceus_ against _Aspergillus_ sp., _Fusarium_ sp., and _Penicillium_ sp. was due to the synthesis of other metabolites [137]. Through an HPLC analysis of antagonistic bacteria supernatants, they detected two antifungal cyclic dipeptides, cyclo (Phe-Pro) and \begin{table}
\begin{tabular}{p{128.0 pt} p{128.0 pt} p{128.0 pt}} \hline \hline
**LAB Species** & **Experimental Condition** & **Summary of Results** & **Reference** \\ \hline _Lactococcus lactis_ (Genome accession No. JADBC000000000), _Enterococcus fractium_ (Genome accession No. JADBC000000000), _Enterococcus fractium_ (Genome accession No. JADBCB000000000) & In vitro despite no ability of phytohormone production. & [PERSON] et al. [18] \\ \hline _Lacticaseibacillus paracasei_ & Field and pot & Improving seed germination rate and growth of tomato. Inducing tolerance against infection by pathogen (_Ralstonia solanacarum_) in seedlings. & [PERSON] et al. [125] \\ \hline _Lactococcus lactis_ & Field & Improving the basil plants’ tolerance against a pathogen (_Alternaria_ sp.). & [PERSON] et al. [126] \\ \hline _Lactobacillus amyloverous_ FST 2.11; DSM 20522 (*) & Field and pot & Revealing the favorable effect on the expression of some defense-related marker genes and transcription factors in barley plants upon Fusarium head blight. & [PERSON] et al. [127] \\ \hline _Enterococcus_ sp. CL2 (accession No. KJ124182.1), _Enterococcus casselfitlaws ZZUA83 (accession No. LC119138.1) & In vitro & Showing high ability in phosphate solubilization and IAA production. & [PERSON] et al. [109] \\ \hline _Weissella paramesterooides_ CE.3.6 _Liquorilactobacillus sucicola_ & In vitro & Inhibiting the growth of _Penicillium digitatum_ as a pathogen agent in citrus fruits. [PERSON] et al. [128] \\ \hline _Lactobacillus_ spp. Pot & Causing systemic acquired resistance (SAR) in tomato plants by changing the morphology, resulting in resistance to fungal pathogens. & [PERSON] et al. [129] \\ \hline _Lactobacillus_ spp. & Field and in vitro & Showing antifungal activities and controlling some important plant pathogenic fungi, such as _Fusarium verticilloides_, _Penicillium sp._, and _Verticillium dahilia in maize._ & [PERSON] et al. [130] \\ \hline _Levilactobacillus brevis_ J2P, _Lactobacillus reuteri_ R2 & In vitro & Inhibition of _Zymoseptoria tritici_ in wheat seedlings and reducing the growth of wheat leaf blotch. & [PERSON] et al. [131] \\ \hline _Pediococcus pentosaceus_ LB44, _Weissella confusa_ LM85 & In vitro & Effective antibacterial potential against a broad spectrum of Gram-positive and Gram-negative bacteria. & [PERSON] and [PERSON] [132] \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Cont.